The term 'REFRAIN START' can be broken down into two crossword solutions: TRA (3 letters) and TRALA (5 letters). TRA is an abbreviation for the musical term 'tempo ritardando', which means to gradually slow down the tempo of a piece of music. TRALA is an abbreviation for the musical term 'tremolo arpeggio lascivamente accelerando', which means to gradually speed up the tempo of a piece of music while playing a tremolo arpeggio.